In recent years, scanner systems have widely been employed in the field of printing plate making. There are various recording apparatus which make practical use of image formation processes by these scanner systems. Glow lamps, xenon lamps, tungsten lamps, LEDs, He-He lasers, argon lasers, and semiconductor lasers, for instance have been used as recording light sources for these scanner system recording apparatus.
The light-sensitive materials to be applied to these scanners are required to exhibit various properties. In particular, since a scanner system recording needs an exposure for a short period of time, such as 10.sup.-3 to 10.sup.-7 second, the light-sensitive materials are required to exhibit a high sensitivity and a high contrast under such conditions. Specifically, in the field of facsimile telecommunication, these light-sensitive materials need to exhibit a high rapid developability in order to meet the required rapid reception of data. In the future, it will be desired to expedite scanning, increase the number of scanning lines and further converge light beams to provide a higher picture quality. A light-sensitive material which exhibits a high sensitivity and a high contrast has therefore been desired.
The term "rapid developability" as used herein means the capability of being processed in 20 to 60 seconds between the time at which the leading edge of the film is introduced into the automatic developing machine and the time at which the leading edge of the film comes out of the automatic developing machine via a developing bath, a connecting section, a fixing bath, a connecting section, a washing bath and a drying section. When the conveying speed in the automatic developing machine is raised to reduce the time required for these processing steps, various troubles may arise such as (1) a reduction in contrast, (2) unthorough fixing, (3) unthorough rinse, and (4) unthorough drying.
In general, it is advantageous to raise the silver chloride content of the silver halide emulsion to solve troubles (1) and (2). However, this approach is disadvantageous in that is causes a reduction in the sensitivity of the light-sensitive material. In order to solve troubles (2), (3) and (4), it is effective to reduce the coated amount of silver and the gelatin content in the silver halide light-sensitive material. However, it is necessary to reduce the size of the grains contained in the silver halide emulsion in order to make up for the resulting reduction in the blackened density and the deterioration in the graininess. In this regard, too, there is a need for a light-sensitive material which comprises a silver halide emulsion with a high silver chloride content, but still exhibits a high sensitivity. The inventors found that these objects can be effectively accomplished by incorporating iridium compounds, iron compounds, rhenium compounds, ruthenium compounds and osmium compounds in silver halide grains. However, this approach is disadvantageous in that although it provides a high sensitivity, it easily causes fogging and also easily gives a low sensitivity and contrast when the development time is short.